Mems pressure sensor based on frequency detection principle and preparation method

Abstract

The MEMS pressure sensor based on the principle of frequency detection adopts a planar spiral inductor, and a MEMS variable parallel plate capacitor is set on one side of the inductor to form an LC resonant circuit; the MEMS capacitor is connected in parallel between the CPW signal line and the ground wire, and its upper pole The plate is a CPW signal line, and the upper plate is directly placed on the MEMS film, and a groove is set on the substrate directly below the MEMS film, and the lower plate of the MEMS capacitor is located on the bottom surface of the groove and two sides close to the ground wire and connected to the ground wire; both ends of the MEMS film are placed on the ground wire to form a closed cavity with the groove. The closed cavity is used to sense the external pressure. When the pressure difference between the inside and outside of the closed cavity changes, the MEMS film deflects, causing the capacitance between the upper plate and the lower plate of the MEMS capacitor to change, which makes the RF signal on the CPW transmission line The resonant frequency shifts, and the detected pressure can be characterized by measuring the resonant frequency value.

Description

Technical field [0001] The present invention relates to RF microelectromechanical systems (the RF MEMS) technology, and in particular relates to MEMS pressure sensor and a method of preparation based on the frequency detection principle. Background technique [0002] The pressure sensor can feel the pressure signal and the pressure signal according to certain rules and easy conversion device to measure the electrical output signal. It is widely used in automotive electronics, automation, aerospace, biomedical, environmental monitoring, is one of the industry commonly used sensors. With the development of MEMS technology, microfabrication of a pressure sensor having a MEMS process miniaturization, low power consumption, and other advantages mass; Depending on the type of stress test, the pressure sensors can be divided into type gauge, absolute and differential pressure three types of compression, according to the principle of different pressure tests, which can be divided into pr...

AI Technical Summary

Problems solved by technology

The piezoresistive pressure sensor is based on the principle of piezoresistive effect of semiconductor materials (such as polysilicon, etc.). The principle of variable quantity has high sensitivity, but poor linearity and is susceptible to interference; piezoelectric pressure sensors are based on the principle of piezoelectric effect of materials (such as PZT, AlN, etc.), and their response speed is fast, but piezoelectric materials The preparation is complicated, and some parts are difficult to be compatible with the standard process; the resonant pressure sensor is based on the principle that the resonant frequency of the structure changes with the pressure, and its sensitivity is high, but because the pressure change has little change in the frequency offset, its resolution is not high

Images